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92 Cards in this Set
- Front
- Back
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esophagus
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a straight muscular tube 25-30 cm long, junction with stomach at T11.
begins at level between C6 and the cricoid cartilage extends from pharynx to cardiac orifice of stomach passing through esophageal hiatus in diaphragm The esophagus passes through the esophageal hiatus and enters the abdominal cavity. |
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lower esophageal sphincter
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– food pauses at this point because of this constriction
prevents stomach contents from regurgitating into the esophagus protects esophageal mucosa from erosive effect of the stomach acid heartburn – burning sensation produced by acid reflux into the esophagus nonkeratinized stratified squamous epithelium skeletal muscle in upper one-third, mixture in middle one-third, and only smooth muscle in the bottom one-third Passes through right crus of diaphragm at T10. |
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Esophagus is constricted at the
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pharyngeoesophageal junction (upper espophageal sphincter), the tracheal bifurcation (thoracic constriction) and the esophageal hiatus.
Esophagogastric junction at T11 Thoracic vasculature esophageal branch of thoracic aorta esophageal veins=>azygos system => systemic circulation |
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Abdominal vasculature
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left gastric artery and left inferior phrenic artery
left gastric vein=> portal system esophageal varices and portal hypertension Lymph nodes left gastric=> celiac lymph nodes Nerves esophageal plexus (branches of vagal trunks) |
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Stomach
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a muscular sac in ULQ immediately inferior to the diaphragm that primarily functions as a food storage organ.
internal volume of about 50 mL when empty 1.0 – 1.5 L after a typical meal up to 4 L when extremely full and extend nearly as far as the pelvis Mechanically breaks up food particles, liquefies the food, and begins chemical digestion of protein and fat chyme – soupy or pasty mixture of semi-digested food in the stomach Most digestion occurs after the chyme passes on to the small intestine |
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Why is the stomach retained--why not remove the entire stomach?
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Parietal cells, intrinsic factor, prevent pernicious anemia
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pylorus looks ____ while fundus looks ______.
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pudgy; feathery
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How does the function of the fundus and pylorus differ?
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Pylorus releases hormones
Fundus releases enzymes |
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ANS: Parasympathetic distribution
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Left vagus=>anterior vagal trunk=>anterior gastric branches (anterior stomach)
Right vagus=>posterior vagal trunk=>posterior gastric branches |
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What is the general effect of the PSNS upon the stomach?
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increase flow/digestion
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ANS Regulation: Sympathetic distribution
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T6-T9=>greater splanchnic nerve=>celiac ganglion
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vessels of the stomach
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Lesser curvature
left and right gastric aa Greater curvature l and r gastro-omental and short gastric aa |
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Branches of the celiac trunk supply the ________.
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upper abdominal viscera
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What organ is most likely to be compromised if there is a slow perforation of the posterior stomach wall? What major branch of the celiac trunk may erode?
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pancreas; splenic artery
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hepatic portal system circulation pathway
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R & L gastric veins from greater curvature => hepatic portal vein
Others (splenic, gastro-omentals, short gastrics) eventually => superior mesenteric v => hepatic portal v |
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What is the purpose of delivering blood to the portal system?
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filter toxins etc.
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In gastric bypass why bypass the duodenum?
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all of the digestive enzymes bile etc that are put here need to be avoided
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the small intestine
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Longest portion, this is where almost all digestion and absorption takes place.
1” in diameter, 21’ long. Extends from the pyloric sphincter to the ileocecal valve. Surface area |
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duodenum
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– the first 25 cm (10 inches) receives stomach contents, pancreatic juice, and bile; stomach acid and pepsin is neutralized here; fats are physically broken up (emulsified) by the bile acids
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jejunum
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– first 40% of small intestine beyond duodenum is especially rich blood supply which gives it a red color; most digestion and nutrient absorption occurs here
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ileum
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forms the last 60% of the postduodenal small intestine is thinner, less muscular and less vascular than the jejunum.
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Peyer patches
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prominent lymphatic nodules in clusters on the side opposite the mesenteric attachment that are readily visible with the naked eye.
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The Duodenum Is Divided Into Four Sections
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First part (superior portion, A+B) is suspended by the hepatoduodenal ligament
Anterior of remainder is covered by peritoneum and is retroperitoneal Second portion (descending, C) is crossed by the tranverse colon ; bile and pancreatic ducts enter here. duodenal ampulla major (maybe minor) duodenal papilla Inferior portion (horizontal portion, D) crosses the IVC Fourth portion (ascending, E) ends at the the duodenal-jejunal flexure supported by the suspensory muscle |
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Which portion of the SI is crossed by the SMA (and SMV)?
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the third portion (inferior portion)
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vascular supply of the duodenum
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The duodenum is supplied by branches of the celiac trunk and superior mesenteric artery (SMA).
Gastroduodenal artery=>superior pancreaticoduodenal artery=>proximal to the duodenal papilla SMA |
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_________ is the second unpaired branch of the abdominal aorta, located around L1. It supplies almost all of the small intestine as well as the proximal half of the large intestine.
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The superior mesenteric artery
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_________ delivers blood to the distal portion of the duodenum.
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The inferior pancreaticoduodenal artery
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Is the spleen an intraperitoneal, extraperitoneal or retroperitoneal organ?
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intraperitoneal
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spleen
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Large vascularized lymphatic organ located in LUQ.
Protected by ribs 9-11 Attached to Greater curvature of the stomach by the gastrosplenic ligament Left kidney by the splenorenal ligament (suspended by) the phrenicocolic ligament (sustentaculum lienis) Splenic a and v |
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Pancreas
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Extraperitoneal organ that lies transversely along the posterior abdominal wall.
Performs both exocrine and endocrine functions. Regions Head overlying the IVC and r&l renal veins, r renal a. Neck, overlying SM vessels Body lying in the floor of the omental bursa Tail anterior to the left kidney Ducts Main pancreatic duct => major duodenal papilla guarded by sphincter of Oddi. Accessory pancreatic duct => minor duodenal papilla Branches of the splenic a and v supply the pancreas |
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Intraperitoneal organs
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completely covered by visceral peritoneum
liver, spleen , stomach, proximal duodenum, jejunum, ileum,transverse colon, sigmoid colon, proximal rectum. |
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Extraperitoneal organs
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partially covered:
pancreas, ascending and descending colon, adrenals, pancreas Kidneys |
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Do intraperitoneal organs lie in the peritoneal cavity?
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No
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Where are the epigastric and right hypochondriac regions?
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top middle and top right
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What organ is most likely to be compromised if there is a slow perforation of the posterior stomach wall?
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pancreas
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Formation of the Gut Tube
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As a result of cephalocaudal and lateral folding:
Dorsal part of yolk sac is incorporated into the embryo Gut tube extends from oropharyngeal (head end) membrane to cloacal membrane (tail end) Epithelial lining of the gut tube proliferates rapidly (obliterating the lumen) Recanalization must occur |
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Development of primitive gut and its derivatives usually discussed in four sections:
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Pharyngeal gut or pharynx:
extends from buccopharyngeal membrane to tracheobronchial diverticulum important for development of head and neck Foregut lies caudal to pharyngeal tube and extends as far caudally as the liver outgrowth Midgut begins caudal to liver bud and extends to junction of right two-thirds and left third of transverse colon Remains temporally connected to yolk sac via: Vitelline duct (yolk stalk) Hindgut extends from left third of the transverse colon to cloacal membrane |
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Endoderm of primordial gut gives rise to most of its:
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Epithelium
gGands |
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Epithelium at cranial and caudal ends of alimentary tract is derived from ectoderm of:
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Stomodeum
Proctodeum |
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Muscular, connective tissue, and other layers of the wall of the digestive tract are derived from:
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Visceral Mesoderm
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Foregut Derivatives
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Esophagus
Stomach Upper Duodenum Liver, biliary apparatus (hepatic ducts, gallbladder, and bile duct), and pancreas Most foregut derivatives are supplied by celiac trunk |
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Esophagus Development
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Develops from foregut immediately caudal to pharynx
Partitioning of trachea from esophagus occurs via tracheoesophageal septum Formed By tracheoesophogeal folds Initially, esophagus is short Lengthens due to growth and relocation of heart and lungs Epithelium proliferates and partly or completely obliterates lumen |
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Recanalization of esophagus normally occurs by end of ______ week
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eighth
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Esophagus Development
Endoderm gives rise to: Visceral mesoderm gives rise to: |
Stratified squamous epithelium
Mucosal glands Submucosal glands Lamina propria Muscularis mucosa Submucosa Skeletal muscle of muscularis externa |
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Stomach Development
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Distal part of foregut is initially a tubular structure
Around middle of fourth week, slight dilation (fusiform enlargement) indicates site of stomach primordium Enlarges and broadens ventrodorsally During next 2 weeks, dorsal border grows faster than ventral border Greater and Lesser Curvatures Primitive stomach rotates 90° clockwise along its longitudinal axis |
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Effects of Stomach Rotation
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Before rotation, cranial and caudal ends are in median plane
During rotation and growth of stomach: Cranial region moves left and slightly inferiorly Caudal region moves right and superiorly After rotation, stomach assumes its final position with long axis almost transverse to long axis of body Rotation and growth of stomach explain why left vagus nerve supplies anterior wall of adult stomach Right vagus nerve innervates its posterior wall Ventral border (lesser curvature) moves to the right Dorsal border (greater curvature) moves to the left Original left side becomes ventral surface Original right side becomes dorsal surface |
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Stomach Mesenteries
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Suspended from dorsal wall of abdominal cavity by:
Dorsal mesentery (primordial dorsal mesogastrium) Originally in median plane Dorsal mesogastrium carried to left during rotation, forming: Omental bursa or lesser sac of peritoneum Primordial ventral mesogastrium attaches to stomach Attaches duodenum to liver and ventral abdominal wall |
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Stomach Tissue
Endoderm |
Surface mucous cells that line the stomach
Parietal cells Chief cells Enteroendocrine cells |
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Stomach Tissue
Visceral Mesoderm |
Lamina propria
Muscularis mucosa Submucosa Smooth muscle of the muscularis externa Stomach serosal layer |
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Development of the Liver and Biliary Apparatus
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Liver, gallbladder, and biliary duct system arise as:
Ventral outgrowth (hepatic diverticulum) into the mesoderm of the septum transversum Explains close relationship of liver and diaphragm since diaphragm also formed by septum transversum 4th week of development |
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Hepatic Diverticulum
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Enlarges rapidly and divides into two parts as it grows between layers of ventral mesogastrium:
Larger cranial part of hepatic diverticulum is primordium of liver Small caudal part of hepatic diverticulum becomes: Gallbladder Stalk of diverticulum forms cystic duct |
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Larger Cranial Part Of Hepatic Diverticulum: Primordium Of Liver
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Proliferating endodermal cells give rise to:
Interlacing cords of hepatocytes Epithelial lining of intrahepatic part of biliary apparatus Hepatic cords anastomose around endothelium-lined spaces: Primordia of hepatic sinusoids Fibrous and hematopoietic tissue and Kupffer cells of liver are derived from: Mesenchyme in septum transversum |
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Development of the Liver and Biliary Apparatus
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Liver grows rapidly and, from 5th to 10th weeks, fills a large part of upper abdominal cavity
Quantity of oxygenated blood flowing from umbilical vein into liver determines development and functional segmentation of liver Initially, right and left lobes are approximately same size Right lobe becomes larger Hematopoiesis begins during sixth week, giving liver a bright reddish appearance By ninth week, liver accounts for approximately 10% of total weight of fetus Bile formation by hepatic cells begins during 12th week |
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Gall Bladder Development
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Connection between the hepatic diverticulum and foregut narrows to form the bile duct
Outgrowth of bile duct gives rise to early gallbladder and cystic duct Cystic duct divides the bile duct into Common Hepatic Duct Common Bile Duct Proliferation of endodermal lining of gallbladder and extrahepatic ducts close of the lumen, but recanalization occurs later |
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Extrahepatic Biliary Apparatus
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Initially, occluded with epithelial cells
Later re-canalized Stalk connecting hepatic and cystic ducts to duodenum becomes: Bile duct Initially, bile duct attaches to ventral aspect of duodenal loop As duodenum grows and rotates, entrance of bile duct is carried to dorsal aspect of duodenum Bile entering duodenum through bile duct after 13th week gives meconium (intestinal contents) a dark green color |
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Liver and biliary tissue
Endoderm |
Hepatocytes
Simple columnar or cuboidal epithelium |
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Liver and biliary tissue
Mesoderm |
Kupffer cells
Hematopoietic cells Endothelium of sinusoids Fibroblasts of liver |
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Liver and biliary tissue
Visceral Mesoderm |
Lamina propria of gall bladder
Muscularis externa of gall bladder Adventitia of gallbladder |
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Pancreas Development
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Develops between layers of mesentery from:
Dorsal and ventral pancreatic buds of endodermal cells Arise from caudal or dorsal part of foregut Larger dorsal pancreatic bud gives rise to most of pancreas Appears first and develops a slight distance cranial to ventral pancreatic bud Grows rapidly between layers of dorsal mesentery |
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Ventral Pancreatic Bud
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Develops near entry of bile duct into duodenum
Grows between layers of ventral mesentery As duodenum rotates to the right and becomes C-shaped Ventral pancreatic bud is carried dorsally with bile duct It soon lies posterior to dorsal pancreatic bud Later fuses with it Ventral pancreatic bud forms: Uncinate process Part of head of pancreas |
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As Pancreatic Buds Fuse, Their Ducts Anastomose
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Pancreatic duct forms from:
Ventral bud duct Distal part of dorsal bud duct Proximal part of pancreatic duct from dorsal bud often persists as: Accessory pancreatic duct Opens into minor duodenal papilla Located approximately 2 cm cranial to main pancreatic duct The two ducts often communicate with each other In approximately 9% of people, the pancreatic ducts fail to fuse, resulting in two ducts |
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Pancreatic tissue
Endoderm |
Acinar cells
Islet cells Simple columnar or cuboidal epithelium lining of ducts |
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Pancreatic tissue
Visceral Mesoderm |
Connective tissue of pancreas
Vascular components of pancreas |
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development of the spleen
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Vascular lymphatic organ derived from:
Mesenchymal cells located between layers of the dorsal mesogastrium Begins to develop during fifth week Does not acquire its characteristic shape until early in fetal period As stomach rotates: Left surface of mesogastrium fuses with peritoneum over left kidney This fusion explains: Dorsal attachment of splenorenal ligament Why adult splenic artery (largest branch of celiac trunk) follows a tortuous course: Posterior to omental bursa Anterior to left kidney |
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Duodenum Development
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Early in fourth week, duodenum begins to develop from:
Caudal or distal part of foregut Cranial or proximal part of midgut Splanchnic mesenchyme associated with these endodermal parts of primordial gut Junction of two parts of duodenum is: Distal to origin of bile duct Developing duodenum grows rapidly, forming: C-shaped loop that projects ventrally As stomach rotates, duodenal loop rotates to right and comes to lie retroperitoneally (external to peritoneum) Because of its derivation from foregut and midgut, duodenum is supplied by: celiac trunk superior mesenteric artery |
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Midgut Derivatives
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Small intestine, including duodenum distal to bile duct opening
Cecum Appendix Ascending colon Proximal 2/3 of transverse colon Midgut derivatives are supplied by: Superior mesenteric artery (midgut artery) |
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Elongation of the Midgut
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Forms a ventral, U-shaped loop of gut:
Midgut loop of the intestine Projects into remains of extraembryonic coelom in the proximal part of umbilical cord At this stage, intraembryonic coelom communicates with extraembryonic coelom at the umbilicus |
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Midgut Loop of the Intestine
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Is a physiologic umbilical herniation
Occurs at beginning of sixth week Loop communicates with umbilical vesicle through narrow omphaloenteric duct (yolk stalk) until 10th week Physiologic umbilical herniation occurs because: Not enough room in abdominal cavity for rapidly growing midgut Shortage of space is caused mainly by relatively massive liver and kidneys |
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Midgut Loop of the Intestine: Two Limbs
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Two limbs suspended from dorsal abdominal wall by an elongated mesentery:
Cranial (proximal) limb Caudal (distal) limb Omphaloenteric duct is attached to: Apex of midgut loop where two limbs join Cranial limb grows rapidly and forms: Small intestinal loops Caudal limb undergoes very little change except for development of: Cecal swelling (diverticulum), primordium of cecum and appendix Large intestine |
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Within In The Umbilical Cord
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Midgut loop rotates 90 degrees counterclockwise (looking from ventral side) around axis of superior mesenteric artery
Cranial limb (small intestine) of midgut loop moves right Caudal limb (large intestine) to the left During rotation, cranial limb elongates and forms: intestinal loops (primordia of jejunum and ileum) |
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Intestines Return to Abdomen (Reduction Of Midgut Hernia)
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During Week 10
It is not known what causes intestine to return; however the following are important factors: Enlargement of abdominal cavity Relative decrease in size of liver and kidneys Small intestine (formed from cranial limb) returns first: Passing posterior to superior mesenteric artery and occupies central part of abdomen |
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Large Intestine (Caudal Limb of Midgut Loop) Returns
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Undergoes a further 180-degree counterclockwise rotation
Later comes to occupy right side of abdomen Ascending colon becomes recognizable as posterior abdominal wall progressively elongates |
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Cecum and Appendix
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Cecal swelling (diverticulum) appears in sixth week as an elevation on the antimesenteric border of the midgut loop caudal limb:
Primordium of cecum and wormlike (L., vermiform) appendix |
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Midgut Tissue
Endoderm |
Simple columnar absorptive cell linings
Goblet cells Paneth cells Enteroendocrine cells of the intestinal glands |
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Midgut Tissue
Visceral Mesoderm |
Lamina propria
Muscularis mucosa Submucosa Smooth muscles of the muscularis externa Serosal layer |
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Hindgut Derivatives
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Distal 1/3 transverse colon
Descending colon Sigmoid colon Rectum Superior part of anal canal Epithelium of urinary bladder and most of the urethra |
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Artery Supply of Hindgut Derivatives
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Inferior mesenteric artery
Artery of the hindgut Junction between segment of transverse colon derived from midgut and that originating from hindgut is indicated by: Blood supply change from superior mesenteric artery branch (midgut artery) to a inferior mesenteric artery branch (hindgut artery) |
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Cloaca
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L., sewer
Expanded terminal part of hindgut Endoderm-lined chamber Cloaca is in contact with surface ectoderm at: Cloacal membrane, which is composed of: Endoderm of cloaca Ectoderm of the proctodeum (L., anus) or anal pit Cloaca receives: Allantois ventrally, which is a fingerlike diverticulum |
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Partitioning of the Cloaca
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Cloaca is divided into:
Dorsal and ventral parts by a wedge of mesenchyme: Urorectal septum Develops in the angle between allantois and hindgut |
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Urorectal Septum
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Grows toward cloacal membrane
Develops forklike extensions that produce infoldings of the lateral walls of the cloaca These folds grow toward each other and fuse, forming a partition that divides cloaca into two parts: Rectum and cranial part of anal canal, dorsally Urogenital sinus, ventrally |
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By Seventh Week, Urorectal Septum Has Fused With Cloacal Membrane
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Dividing it into:
Dorsal anal membrane Larger ventral urogenital membrane Area of fusion represented in adult by: Perineal body, tendinous center of perineum Fibromuscular node is landmark of perineum where several muscles converge and attach |
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Anal Membrane Usually Ruptures At End Of Eighth Week
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Brings distal part of digestive tract (anal canal) into communication with amniotic cavity
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Anal Canal
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Superior two thirds of adult anal canal are derived from:
Hindgut Inferior one third develops from: Proctodeum Ectodermal part of alimentary canal Junction of the epithelium derived from proctodeum ectoderm and hindgut endoderm is indicated by: Irregular pectinate line Located at inferior limit of the anal valves This line indicates approximate former site of anal membrane |
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Superior Two-Thirds of Anal Canal
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Because of its hindgut origin, mainly supplied by:
Superior rectal artery Continuation of inferior mesenteric artery (hindgut artery) Venous drainage is mainly via: Superior rectal vein Tributary of inferior mesenteric vein Lymphatic drainage is eventually to: Inferior mesenteric lymph nodes Nerves are from the autonomic nervous system |
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Inferior One-Third of Anal Canal
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Because of its origin from the proctodeum, it is supplied mainly by:
Inferior rectal arteries branches of the internal pudendal artery Venous drainage is through: Inferior rectal vein Tributary of internal pudendal vein that drains into internal iliac vein Lymphatic drainage is to: Superficial inguinal lymph nodes Its nerve supply is from: Inferior rectal nerve It is sensitive to pain, temperature, touch, and pressure |
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Hindgut Tissues
Endoderm |
Simple columnar absorptive cell linings (through upper anal canal)
Goblet cells Enteroendocrine cells of the intestinal glands |
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Hindgut Tissues
Visceral Mesoderm |
Lamina propria of hindgut derivatives (except anus)
Muscularis mucosa of hindgut derivatives (except anus) Submucosa of hindgut derivatives (except anus) Smooth muscles of the muscularis externa of hindgut derivatives (except anus) Serosal layer of hindgut derivatives (except anus) |
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Hindgut Tissues
Mesoderm |
Lamina propria of anus
Muscularis mucosa, submucosa and muscularis externa of anal sphincters |
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Hindgut Tissues
Ectoderm |
Simple columnar and stratified columnar epithelial lining of lover anal canal
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Dorsal and Ventral Mesenteries
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The primitive gut is intraperitoneal
Suspended in the peritoneal cavity by the dorsal mesentery which enables it to move left and right from the midline Increases in gut size and length during development causes the dorsal mesentery to grow During gut fixation, some parts of the gut eventually become attached to the posterior body wall and are thus referred to as retroperiotoneal Duodenum Ascending Colon Descending Colon |
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Ventral Mesentery
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Thin, double-layered membrane derived from mesogastrum gives rise to:
Lesser omentum Passing from liver to lesser curvature of stomach (hepatogastric ligament) Passing from liver to duodenum (hepatoduodenal ligament) Falciform ligament Extending from liver to ventral abdominal wall Coronary liver ligament Triangular liver ligament Umbilical vein passes in free border of falciform ligament On its way from umbilical cord to liver Ventral mesentery also forms: Visceral peritoneum of the liver Liver is covered by peritoneum except for bare area that is in direct contact with diaphragm |
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Dorsal Mesentery
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Double layer of mesothelium that suspends the gut from the dorsal wall of the foregut to the hindgut
Gives rise to greater omentum, mesentery of small intestine, transverse mesocolon, sigmoid mesocolon, mesoappendix |
